A swept sine wave analyzer or network analyzer is typically used to measure the frequency response or transfer function of a circuit or device under test (DUT). A spectrally pure swept sine wave stimulus is injected into the circuit or DUT. The measurement is made by monitoring two signal points at the DUT. One signal point serves as the input and the other serves as the output. The DUT response at each frequency is measured and stored. This continues for a predetermined number of steps over a predetermined frequency range. Calculations are performed on the results of this sequence of measurements to yield the frequency response or transfer function of the DUT.
Various electronics industries use analyzers such as the one described above to characterize their systems. Some example devices or systems include audio amplifiers, power supply controls, radio frequency amplifiers, motor controllers and any circuit or system where it is important to characterize frequency response.
Frequency response measurements are necessary in audio amplifiers so as to characterize their gain uniformity or flatness over all frequencies of the audio bandwidth. Power supply and motor control circuits that utilize feedback for precise regulation utilize magnitude and phase measurements to indicate the degree of control loop stability. Those involved with digital signal processing rely on frequency response measurements to yield transfer functions of the analog systems they are replicating digitally such as IR/FIR filters, hilbert transformers, integrators, differentiators, waveform generators and other systems.
Commercial analyzers are fairly expensive and, in most cases, out of the price range for many electronic designers and companies that could otherwise benefit from testing the frequency response of their systems. The high price also excludes most private contract design engineers, university laboratories, students and electronics hobbyists from being able to have access to them.
Another drawback of commercially available analyzers is that they are stand alone devices without a standard way of connection to a computer. Consequently, the transfer of information to a computer is cumbersome and may require any one of or a combination of the following:                special programming skill of the operator,        custom cabling,        interface card installed in the computer,        purchase of additional software for control and data analysis,        manually saving the test data to a floppy disk located on the analyzer for transfer to a computer. After being saved, the data from the floppy is loaded into an application running on the computer.        
This involves unnecessary steps for the engineer or researcher who would like the data readily available to incorporate into their documentation or data analysis applications.